Rotary pump



NW7. 25 1924. 1,516,591 H. D. EDWARDS ROTARY PUMP Filed pril 30.. 1923 s Sheets-Sheet 1 INVENTOR A TTORNE Y 1,516,591 H. D. EDWARDS ROTARY PUMP Filed April 30. 1923 3 Sheets-Sheet A TTORNEY wmsn NQW. 259

H. D. EDWARDS ROTARY PUMP Filed April 30. 1923 3 Sh@atsheet 5 INVENTOR A TTORNE Y Patented Nov. 25, EOZt.

i or rr e' 'rc HARRY D. EDWARDS, OF LAROHMONT, NEW YORK, ASSIGNOR TO THE HILL COM- PRESSOR & PUMP COMPANY, OF NEW YORK, N.

Y., A CORPORATION OF DELAWARE.

ROTARY PUMP.

Application filed April 30,1923. Serial No. 635,523.

To all whom it may concern:

Be it known that I, HARRY D. EDWARDS, a citizen of the United States, residing at Larchmont, in the county of Westchester and State of New York, have invented a new and useful Improvement in Rotary Pumps, of which the following is a specification. 1

This invention relates to those rotary pumps which have agear with external teeth that is surrounded by a gear with internal teeth, one gear having more teeth than the other and the two gears being mounted eccentrically with relation to each other and so intermeshing that when driven, fluid admitted through the enclosing casing on the intake side will be compressed and deliv cred through the casing on the discharge side.

In this type of pumps it is essential, in order that the gear teeth be properly engaged for eflective pumping, that the amount of eccentricity of the gears be such that the pitch circles of the gear teeth be tangent with each other at one point.

The object of this invention is to provide a pump of this character with means whereby the eccentricity of the gears with relation to each other may be accurately fixed, and thus the proper co-operation of the gear teeth ensured to effect etficient pumping action.

This object is attained in the embodiment ofrthe invention illustrated by mounting the' externally toothed gear which is surrounded by the internally toothed gear, on an arbor that is supported eccentrically of the axis of the internally toothed gear, and providing means whereby the eccentricity of said an bor may be varied to enable the exact required position of the externally toothed gear with relation to the internally toothed gear to be obtained and retained.

In the accompanying drawings Fig. 1 shows a longitudinal section of one form of pump constructed according to this invention. Fig. 2 shows, on a larger scale, a face view of the gears that may be used, and illustrates diagrammatically the shapes of the engaging gear teeth and eccentricity of the gears. Fig. 3 shows diagrammatically in full lines the pitch circles of the ear teeth when so adjusted that the eccentricity of the gears is correct, and illustrates in dotted lines a possible position of the pitch circle of the externally toothed gear before it is properly adjusted to the pitch circle of the internally toothed gear.

In the form of the invention illustrated the pump casing 1 is cylindrical and it has a head 2 fastened in such manner that it may be removed to allow access to the interior of the gear chamber in the casing. Through the head to the gear chamber is an intake opening 8 and a discharge opening 4:. In the gear chamber is a gear 5 with external teeth 6, and a gear 7 with internal teeth 8 that surround and mesh with the external teeth. For the purpose ofmanufacture the internal teeth are cut in a ring that is forced into the gear body 7. YThe internally toothed gear has a central hub 9 that is supported by bearings 10 in the casing, and that is keyed to the driving shaft 11. The externally toothed gear is shown as arranged to turn on bearings 12 mounted on an arbor 13 which has a journal 14 that is after adjustment locked in the head.

The internally toothed gear and the driving shaft are axially concentric, and the externally toothed gear and its arbor are axially concentric. but the axis of the arboris eccentric to the axis of the driving shaft so that the axes of the gears will be eccentric, and the axis of the journal is eccentrio with the axis of the arbor and also eccentric with the axis of the shaft so that the eccentricity of the arbor and shaft, or of the two gears, may be adjusted to an exact degree by rotating the journal.

In the particular example illustrated the externally toothed gear has eight teeth and the internally toothed gear has nine teeth. This number of teeth is not essential to the invention, nor is the exact shape of the teeth.

The addendum sections 15, or the portions beyond the pitch circle 16 of the teeth of the inner gear shown, are formed on epicycloidal curves, that is, curves traced by a '1 upon the inside 65 and sealing contact.

pointon the circumference of the circle 17 a which rolls upon the convex surface of another circle, which latter circle in this case is the pitch circle 16 of the inner gear. The 5 dedendum sections 18, or portions insideof the pitch circle 16 of the teeth, of the inner gear, are formed on hypoc'ycloidal curves, that is, curves, traced by a point on the circumference of a circle 17 which rolls upon the inside surface of the pitch circle 16.

The addendum sections 19 of the teeth of the outer gear are formed on hypocyloidal 'the' hecessary tangency of the pitch circles curves, that is, curvestraced by a point on the circumference of the circle 20 which rolls surface of the pitch circle 21 of the outer gear, while the dedendum sections 22 of the teeth of the outer gear are formed on epicycloidal curves, that is, curves 'traced by a point on the circumfer- D ence of the circle 20 which rolls on the convex surface of the pitch circle 21 of the I outer gear. The circles 17 indicated as rolling on the outside and the inside of the pitch circle of the inner. gear, and the circles' 20, indicated as rolling on the outside and inside of the pitch circle of the outer ar, icycloidal and hypocycloidal curves of t e gear teeth, are the same in diameter, 80 and the diameter of these circles is the correct amount of eccentricity of the inner gear to the outer gear.

With this construction the gear teeth conas the internally tact in various relations toothed gear is rotated and drives the externally toothed gear, and this contact of the teeth is rolling, or in the nature of the contact of two cy inders.- As the gears rotate the spaces between the teeth from the point '23, where the teeth bottom, and the pitch circles 16 and 21 of the. two gears are tangent to the point 24 where the crests of the teeth engage,'increase, while thespaces between the teeth from the point of crest engagement to the bottoming point, de-

crease, and a close seal ismadebetween the gear teeth on the compression side.

In order to attain this requiredresult in pumps having the particular form of teeth described, and also teeth of other forms which are commonly used, or may be used,

it is necessarylthat the pitch circles of. the

two gears, w ich are eccentrically related,

. should be exactl tangent at one point; In

Fi 2 and 3 t'is point is at 25. In the 'or inary manufacture, and particularly in tpllantity'productiomjt is diflicult to obtain e exact eccentric relation of the gears, and

it is the" special object of this invention to be able to, in a very simple and easy manner, obtain the correct eccentricity between the centers of the gears which will result in the pitch circles being tangent so that the teeth will properly e go with a rolling stated, the arbor for illustrating the generation of the ment of the vexternall erefore, as abovewhich is eccentric with the driving shaft is provided withan adjustable journal that is eccentric with relation to the arbor and to the driving shaft.

The preferred manner of accom lishing this adjustment is die rammatically illustrated in Fig. 3, which s ows the pitch circle 16 of the externally toothed gear represented in dotted 'lines as having an improper eccentricity with relation to the pitch circle 21 of the internally toothed gear, and in full lines as incorrect position to insure of the two gears to produce the desired results. In the diagrammatic view the point 26 is the axis of the internally toothed gear,

and the point 27 is the axis of the externally toothed gear. The p oint 28 represents the axis of the eccentric ournal of the arbor which supports-the externally toothed gear. The radius 29.0f the circle 30 indicates the correct amount of eccentricit of the gears. Therefore the point 27, which is the center of the arbor and the externally toothedflgear, must when in correct position be somewhere on the circle 30.- With the construction il- The journal may be provided with any convenient means for turning .it, as a slot 31 for a screw driver orother tool, and'after the proper adjustment is made the parts may be secured by any suitable means as by driving a locking pin 32 between them.

This principle of construction allows any slight error in the eccentricity of the gears, such as is liable to occur during manufacture, to be quickly corrected, and this also permits any future adjustment of the gears to be made, if such should become necessary.

The invention claimed is v 1. A rotary pump comprising a casing, a shaft journalled in the casing, an inter-. nally toothed gear mounted centrally on the shaft, an externally toothed gear eccentric within and co-acting with the internally toothed gear, and arbor for, and central with, the externally toothed gear, and a rotatable journal for the arbor, the axes of the arbor and journal being eccentric to each other and each of said axes being eccentric to the axis of the shaft whereby by the rotation. of said journal the eccentric. adjusttoothed gear relatively to the internal y toothed gear may be eifected.

2. A rotary pump comprising a cas- Ill ing, a shaft journalled in the casing, an. internally toothed gear mounted centrally on the shaft, an externally toothed gear eccentric within and co-acting with the internally-toothed gear, a support for, and central with, the externally toothed gear, and

a rotatable journal for said support, the axes of the support and ournal being eccentric to each other and each of said axes being eccentric to the axis of the shaft.

v the externally toothed gear, said support to the axis of the internal] being rotatably mounted in the casing eccentric to the axes of both gears, whereby the eccentricity of the axis of the externally toothed gear may be adjusted relatively toothed gear to ensure the tangency of t e pitch circles of the gears.

41. A rotary pump having a casing containing an internally toothed gear, an externally toothed gear surrounded by the internally toothed gear and eccentric thereto, a normally stationary support for the externally toothed'gear, said support being rotatably mounted in the casing eccentric to the axes of both gears, whereby the cocentricity of the axis of the externally toothed gear may be adjusted relatively to the axis of -the'externally toothed gear to ensure the tangency of the pitch circles of the gears, and means for locking said adjustable support against movement after it. has been set in the desired adjustment.

5. A rotary pump haying a casing enclosing an internally toothed gear, an externally toothed gear surrounded by the internally toothed gear, a normally stationary ar- -bor supportlng said externally toothed gear with its axis eccentric with relation to the axis of said internally toothed gear, and

means extending to the exterior of the casing for adjusting the axis of the arbor with relation to the axis of the internally toothed gear.

' 6. A rotary pump comprising a casing. containing an internally toothed gear, an

externally toothed gear surrounded by the internally toothed gear and eccentric thereto, an arbor supporting the externally toothed gear, and a rotatably adjustable journal for the arbor mounted in the casing,

the axis oi the journal being ofi-set from' the axis of the arbor and both axes being ported by the casing for rotating the inter eccentric to the axis of the internally toothed gear, whereby the axis of the ex ternally toothed gear relative, to the axis of the internally toothed gear may be determined by rotatably adjusting said journal.

7. A rotary pump comprlsing a casing containing an internally toothed gear, a shaft extending into the'casing for rotating the internally toothed gear, an externally toothed gear surrounded and engaged by the internally toothed gear, an arbor rotatably sup-porting the internally toothed gear, the axis of said arbor being eccentric to the axis of said shaft, and a journal supporting'the arbor, said journal being rotatably mounted in the casing with its axis eccentric to the axis of the arbor and also eccentric to the axis of the shaft, whereby by rotating said journal the tan ncy of the pitch circle of the externally toot ed gear and the pitch circle of the internally toothed gear may be obtained after the gears have been enclosed in the casing.

8. A rotary pump' comprising a. casing containing an internally toothed gear, a shaft extending into the casing for rotating the internally toothed gear, an externally toothed gear surrounded and engaged by the internally toothed gear, an arbor rotatably supporting the externally toothed gear, the axis of said arbor being eccentric with relation to the axis of said shaft, a journal supporting the arbor, said journal being rotatably mounted in the casing with its axis eccentric to the axis of the arbor and also eccentric to the axis of the shaft, whereby by the rotation of said journal the tangency of the pitch circle of the externally toothed gear and the pitch circle of thetinternally toothed gear may be obtained after the gears are enclosed in the casing, andmeans for locking the journal against rbtation after the required adjustment has been obtained.

9. A rotary pump having a casingcontaining an internally toothed gear, a shaft supported by the casing for rotating the internally toothed gear, an externally toothed gear surrounded and engaged by the internally toothed gear, an arbor rotatably supporting the externally toothed gear,;the

axis of said arbor being eccentric to the axis of said shaft and in a diametrical line extending from the locality of engagement of the crest points of the teeth of the gears through the axis of the shaft to the lomlity of the bottoming of the teeth of the gears,

and a rotatable journal for said arbor, the axis of said journal being eccentric to the axis of the shaft and arbor and out of said,

ing an internally toothed gear, a shaft Sup,-

nally toothed gear, an externally toothed gear surrounded andengaged by the internally toothed gear, normally stationary means rotatably supporting the externally toothed gear, said supporting means being mounted. in the casing with its axis eccentric with relation to the axis of-the internally toothed gear and eccentric to the axis of the externally toothed gear and rotatably adjustable to permit the relations of the axes of the gears to be changed and the tangeney of the pitch circles of the gears to be en sured with the gears enclosed in the casing.

HARRY D. EDWARDS. 

